Regenerative furnaces



United States Pater REGENERATIVE FURNACES Rudolph L. Hasche, JohnsonCity, Tenn.

Application October 2, 1952, Serial No. 312,732

Claims. (Cl. 263-51) The present invention relates to new and improvedheat regenerative masses and apparatus and more particularly toimprovements in regenerative furnaces utilizing horizontally disposedregenerative masses having a horizontal major axis. Still moreparticularly, it relates to novel constructional features inregenerative masses in which the major axis is disposed in a horizontalplane and employing as regenerative units, loosely disposed refractorymaterials such as ceramic tiles which are flat in shape and rest uponeach other with flues or slots formed between the flat surfaces thereofserving as passageways for the gas stream to be heated and the gasstream to be cooled by the regenerative mass.

In Serial No. 129,969, filed November 29, 1949, and now abandoned infavor of U. S. Patents Nos. 2,662,864 and 2,692,131 which arecontinuations in part thereof, are shown ceramic tile units forregenerative masses containing half flues in staggered relationship onboth sides of comparatively thin flat tiles. These tiles with thedimensions specified in the application give remarkable efficiency intransferring heat to or from gas passing through a regenerative mass ofwhich the tiles form a part. The preferred form of regenerative mass isof the horizontally disposed type in which the tiles rest upon eachother by gravity and form a compact mass with equally spaced fluesrunning horizontally through and which are substantially uninterruptedexcept for joints formed by the ends of the tiles.

Although in the past the advantages of a horizontal form of regenerativemass have been recognized, the serious difficulty encountered has beenthe tendency of gas to channel over the top of the regenerative mass. Itis well known to those skilled in the art that flat ceramic tiles whichhave been fired at high temperatures depart somewhat from the trueflatness and even with the greatest care in manufacture show somewarpage. Since the new type of tiles which are preferred, as disclosedin my co pending application, are comparatively thin, a commercialregenerative mass consists of a large number of tiles piled one on topof another and during operation particularly under high temperatures asis encountered in regenerative furnaces, the gravitational weight of thetiles pressing upon each other relieves the warpage and causes return totrue flatness. This causes a considerable compacting of the stack oftiles in a vertical direction and leaves a channel of considerable widthbetween the top of the stack of regenerative tiles and the enclosinginsulating brick at the to Gases being passed through the regenerativemass tend to flow through the channel and hence by-pass the mass itself.This is very undesirable and results in great inefficiencies.

The present invention provides a means for preventing such channelingand hence by-passing of gas around the mass. The present inventionprevents such channeling by providing for a floating top of insulationbrick which lies by gravity on the top of the tile stack and movesupwardly and downwardly therewith so that when the mass has beencompacted there is no channel formed between the tiles and theinsulating brick to cause by-passing of the gas passing through theregenerator. The present invention further provides for a layer ofinsulating, compressed and elastic material between the top of theinsulating brick and the steel shell or top cover of the furnace so thatas the insulating ceramic floating top settles with the regenerativemass, the elastic compressed cushion of material at the top can expandwithout leaving a passage for bypassing of gas.

More specifically the present invention prevents such channeling byproviding a layer of insulating brick located on top of the mass andadapted to float upwardly and downwardly with the top of the mass, 2.layer of compressed elastic material located on top of the floatingbrick, the tendency of the compressed material to expand asserting atleast during the time of tile expansion and preferably at all times acontinuous downward force upon the floating brick, and hence upon thetop mass, the compressed material being adapted to expand upon downwardmovement of the top of the mass and the floating brick, therebypreventing an open space from forming above the mass and hence the gasesfrom by-passing the mass, and

to be compressed by upward movement of the top of said mass and thefloating brick, and means for asserting continuous force upon the top ofthe compressed material to maintain the same in a compressed state atleast during the time of tile expansion, and preferably at all times soas to assert the downward force on the floating brick and the top of themass.

The features of this invention may be applied quite generally toregenerative masses disposed in a horizontal plane and made up of tileunits stacked vertically regardless of the use to which the regenerativemasses are applied. For example, the present invention may be employedfor alternate recovery of heat from blast furnace or reverberatoryfurnace gases and to heating of blast air or combustion air. Theregenerative mass may also be applied to pre-heating air or steam tohigh temperature or it may be applied in a furnace such as thatdescribed in my copending applications Serial Nos. 180,757, filed August22, 1950, 154,185, filed April 5, 1950, 353,361,- filed May 6, 1953, and277,685, filed March 20, 1952, in which chemical reactions are carriedout, for example, in producing reformed gas for heating purposes oracetylene or ethylene.

A typical example of the application of my invention to a furnace forthe production of heating gas will be described as an example.

In Figure I is shown a longitudinal cross-section in a horizontal planethrough a furnace to produce reformed gas for heating purposes. Itconsists of a gas type shell 1 lined with insulating brick 2 and twochambers 15 and 16, containing regenerative masses 3 and 4 separated bya bridge wall 5. A reaction chamber 6 is provided at one end of each ofthe regenerative masses. Such reaction chamber connects the ends of themasses, allowing gas passage therethrough. At the other end of theregenerative masses are chambers 7 and 8 for introducing and withdrawinggases through pipes 9 and 10. To start the furnace a burner 11 isprovided for heating the chamber 6 and the contiguous ends of theregenerative masses 3 and 4 to a temperature of above 1,000 F. Operationis performed by alternating the flow of a mixture of hydrocarbon and airthrough pipes 9 and 10.

Figure II, which is section IIII of Figure I, shows steel gas-tightshell 1, insulating brick 2 and bridge wall 5 providing two likechambers 15 and 16 containing the ceramic tiles which comprise theregenerative masses 3 and 4. These tiles are stacked as indicated in thedrawing and at the top of the stacks are provided floating warpage.

so that free vertical movementis allowed. Tension on 1 ;cqnsisting o fvermiculite.

masses of insulating brick '17 and 18 which are'free to move as, thetiles become compacted due to relief of Joints 19, 20, 21 and 22 arefree-of mortar the floating top 'is;provid'e d for; byrcu'shion's 23.and 26 Thisf'material can, be com pressed manyfold so' that-asthefloating top moves with the compacting of the tile stacks thevermiculite" layer expands'and forms an excellent seal without leaving aa channel for gas by-passing; 'Tension is applied, to the vermiculite bythe steel covering 25; which is part of the ,gas tightshell of thefurnace.

The present invention elimlnatesjthe difiiculty experie'nced inhorizontal furnaces employing regenerative masse s consisting oflOQSfiElf/fdlSPQSQd refractories such ,as loose known types of checkertile stacked one upon theoth erby effectively eliminating gasby-passing.At 7 2,766,980 v v a, n

to expansion, contraction and compacting, said'down-' ward movement ofthe top of said mass resultingin the formation of an open space abovethe top of said mass,

' through which gases by-pass around said mass; the im ithielsameftimethe checker tiles comprising the regenera tive mass are'allowed freedomofmovement due to the expansion and contractionfrmn heat and compactingdue to. relief of war-page. The present invention is partic'ularlyadapted to be used with regenerative masses retained in cavities orchambers with straight vertical 'walls, and which are disposed in ahorizontal plane and in which the major axis is horizontal. Anycompressible finaterial similar to vermiculite may be used as acompressed, elastic material, such as any crushed refractory material orfibrous asbestos. 7 Although the present invention is particularlyadapted to be used with the apparatus herein described, it may 7 j alsobe advantageously applied to any horizontal furnace containing any typesof horizontally disposed masses such as a pebble bed or crackedrefractory bed, etc.

I claim: V a 1 In a regenerative furnace comprising at least onehorizontally disposed regenerative mass having a horizontal major axisand being located within cavities with straightvertical walls, whereinthe top of said mass moves upwardly and downwardly during furnaceoperation due c '4, The furnace of vprovement comprising: a layer ofinsulating brick 10- cated on top of said mass and adapted to floatupwardly and downwardly with the top of said'mass, a layer of compressedelastic material located on top of said insulating brick, saidcompressed material'having a tendency' to expand thereby asserting adownward force upon said floating brick, and hence upon the top, of saidmass, said compressed material being adapted to expand upon downwardmovement of the top ofcsaid mass and said floating brick, therebypreventing said open space from forming and hence said gases fromby-passing said mass, and to be compressed by upward movement of saidtop of said mass and said floating brick, and means for asserting forceupon the top of said compressed, elastic material to maintain thesameinacompressed state so as to. assert mass is perforated throughoutits length by a plurality ofequally spaced straight, uninterruptedflues.

References Cited in the file ofthis patent UNITED STATES PATENTS 335,699Herreshoif Feb. '9, I886 1,341,970 Chantraine June 1, 1920 r 2,089,001Murray Aug. 3,1937

2,205,242 'Davis et al June 18, 1940 2,303,247 Woods Nov. 24, 1942 7claim 1' in which said regenerative

